import 'package:flutter/material.dart';

void main() {
  runApp(SampleApp());
}

class SampleApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Sample App',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyForm(),
    );
  }
}

class MyForm extends StatefulWidget {
  MyForm({Key key}) : super(key: key);

  @override
  _MyFormState createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  // Create a text controller and use it to retrieve the current value.
  // of the TextField!
  final myController = TextEditingController();

  @override
  void dispose() {
    // Clean up the controller when disposing of the Widget.
    myController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Retrieve Text Input'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: TextField(
          decoration: InputDecoration(hintText: "This is a hint"),
          controller: myController,
        ),
      ),
      floatingActionButton: FloatingActionButton(
        // When the user presses the button, show an alert dialog with the
        // text the user has typed into our text field.
        onPressed: () {
          return showDialog(
            context: context,
            builder: (context) {
              return AlertDialog(
                // 通过TextEditingController获取用户输入
                content: Text(myController.text),
              );
            },
          );
        },
        tooltip: 'Show me the value!',
        child: Icon(Icons.text_fields),
      ),
    );
  }
}
